Generally closure devices such as screw-threaded caps of containers with a screw-threaded opening such as a neck can be removed relatively easily by unscrewing. This can be dangerous when the container houses drugs, dangerous chemicals and the like and a child for example unscrews the closure device and gains access to the contents and then takes the contents with possibly harmful or even fatal results.
Closure devices which seek to provide for safer or authorised opening of the container has been proposed, but they are generally complex and expensive.